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London Nurseries. 



work; and within 18 in. of the top of the wall a shelf about a foot wide. 

 These two shelves are for striking cuttings, and for growing very small and 

 young plants. The pots are watered and otherwise managed from the back 

 shed, through openings about 2 ft. high by 3 ft. wide, in the upper part of 

 the back wall. These openings, communicating with the loft of the back 

 shed, are well adapted for the purposes of ventilation in very severe 

 weather. Instead of a lock to each opening, Mr. Knight has formed a 

 passage behind them, the whole length of the shed; so that by locking the 

 the door of this passage, he secures the whole of the openings. The enclo- 

 sure partition is an open paling for the purpose of admitting a free circulation 

 of air. All the rain water that falls on the back shed, the eaves of which, 

 as it is two stories in height and narrow, are higher than those of the glass, 

 is conducted into a cistern in the enclosed passage, for watering the upper 

 shelves ; and all the water which falls on the glass is conducted into a large 

 -tank under the floor of the house, for watering the smaller orange trees on 

 the front shelf, and the large ones in tubs on the floor. The floor is of 

 earth, and might be lowered by excavation 5 or 6 ft., if additional height 

 were wanted for very high old orange trees ; it is now covered with large 

 . old trees in boxes, placed among some half-spent dung and leaves. The 

 door of the house is at one end, in two parts, so that when both are opened 

 there is an opening 6 ft. by 10 ft. for the passage of large trees. 



But the principal feature in this house is the mode of heating it by hot 

 water. If the reader will turn to Vol. IV. p. 29., he will find that the 

 Marquis de Chabannes placed his fire in the middle of a horizontal cylinder 

 of water ; Mr. Knight has greatly improved on this principle by placing his 

 fire in what may be called a flue of water (Jig. 79.). This flue, the top view 

 of which may be seen in^g. 80. a to b, and the side view 

 in the same figure c to d, is about the ordinary size of 

 a hot-house furnace within, and it ascends and gra- 

 dually diminishes to the minimum size of a hot-house 

 flue, at about 18 ft. from the furnace. The outer plate 

 of iron is not more distant than from one half to three 

 fourths of an inch from the inner plate, so that the 

 stratum of water is nowhere more than three fourths of 

 an inch in thickness. This stratum might have been 

 continued under the flue as well as on both sides and 

 the top, but this was not deemed necessary. The 

 rise from the furnace to where this flue boiler assumes the level position 

 (fig. 80. e) is 2 ft.; the exterior sides of the flue are there 18 in. deep, and 



